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Full text of "Text Book Of Mechanical Engineering"

ioo6

Appendix V.

"j\\P. 901. Water Softening. It- is now generally admitted
that the proper place to soften hard feed water is in the feed
tank, and not inside the boiler. The chemicals to be added are
dealt with at p. 901, and it remains to describe a feed- water
softening apparatus for external use. The * Bruun-Lowener y
softener in Fig. 918 is remarkable for its simplicity and small size.
The hard water enters at pipe A, being checked as required by
ball valve B, passing by pipe c c into the cataract vessel D, which
is divided by a mid-partition, so that when one side is filling the
other is emptying. At each discharge of D three things have
been done : the cam roller T has passed under the spindle R,
raising the lever u on centre v, and with it the valve rod w, thus
admitting a certain quantity of liquid chemical from tank Q into
D ; the paddle s has been automatically moved within Q to keep
the chemicals mixed ; and the paddle P has travelled across com-
partment E so as to stir the discharged chemical among the feed
water. The treated water next rises in chamber Y to flow down
the .vertical tube F, but on its way is met by a jet of steam through
pipe M and distributing nozzle N, which has the effect of ac-
celerating the deposition of precipitates, thus reducing the
necessary size of the apparatus. Continuing, the water passes
through filter H and emerges into chamber j, whence it is pumped
through pipe K to the boiler. Mud is withdrawn through cock L.
The apparatus shewn is large enough to supply 400 gallons of
water per hour.

CHAPTER XL

P. 7/0. Density of Fresh Water.- In Fig. 922 a curve
has been prepared to shew accurately the variation in the density
of fresh water between freezing and boiling points. The number
of pounds weight per cubic foot may be read off by means of the
scale on the left of the diagram by measuring the height of the
curve above the base of 60 pounds, referring to the scale, and
adding to it the figure 60.

f, 738. Balanced Hydraulic Lift. Mr. Ellington's lift
described on p. 738 is no longer manufactured on account of the
general objection to internal packings. The Balanced Hydraulic: